// Copyright 2000-2017 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
package qunar.tc.decompiler.code;

import qunar.tc.decompiler.util.TextUtil;

public class Instruction implements CodeConstants {
    public static Instruction create(int opcode, boolean wide, int group, int bytecodeVersion, int[] operands) {
        if (opcode >= opc_ifeq && opcode <= opc_if_acmpne ||
                opcode == opc_ifnull || opcode == opc_ifnonnull ||
                opcode == opc_jsr || opcode == opc_jsr_w ||
                opcode == opc_goto || opcode == opc_goto_w) {
            return new JumpInstruction(opcode, group, wide, bytecodeVersion, operands);
        } else if (opcode == opc_tableswitch || opcode == opc_lookupswitch) {
            return new SwitchInstruction(opcode, group, wide, bytecodeVersion, operands);
        } else {
            return new Instruction(opcode, group, wide, bytecodeVersion, operands);
        }
    }

    public static boolean equals(Instruction i1, Instruction i2) {
        return i1 != null && i2 != null &&
                (i1 == i2 ||
                        i1.opcode == i2.opcode &&
                                i1.wide == i2.wide &&
                                i1.operandsCount() == i2.operandsCount());
    }

    public final int opcode;
    public final int group;
    public final boolean wide;
    public final int bytecodeVersion;

    protected final int[] operands;

    public Instruction(int opcode, int group, boolean wide, int bytecodeVersion, int[] operands) {
        this.opcode = opcode;
        this.group = group;
        this.wide = wide;
        this.bytecodeVersion = bytecodeVersion;
        this.operands = operands;
    }

    public void initInstruction(InstructionSequence seq) {
    }

    public int operandsCount() {
        return operands == null ? 0 : operands.length;
    }

    public int operand(int index) {
        return operands[index];
    }

    public boolean canFallThrough() {
        return opcode != opc_goto && opcode != opc_goto_w && opcode != opc_ret &&
                !(opcode >= opc_ireturn && opcode <= opc_return) &&
                opcode != opc_athrow &&
                opcode != opc_jsr && opcode != opc_tableswitch && opcode != opc_lookupswitch;
    }

    @Override
    public String toString() {
        StringBuilder res = new StringBuilder();
        if (wide) res.append("@wide ");
        res.append("@").append(TextUtil.getInstructionName(opcode));

        int len = operandsCount();
        for (int i = 0; i < len; i++) {
            int op = operands[i];
            if (op < 0) {
                res.append(" -").append(Integer.toHexString(-op));
            } else {
                res.append(" ").append(Integer.toHexString(op));
            }
        }

        return res.toString();
    }

    @Override
    @SuppressWarnings("MethodDoesntCallSuperMethod")
    public Instruction clone() {
        return create(opcode, wide, group, bytecodeVersion, operands == null ? null : operands.clone());
    }
}